platform/x86/amd/pmf: Add support for PMF core layer

PMF core layer is meant to abstract the common functionalities
across PMF features. This layer also does the plumbing work
like setting up the mailbox channel for the communication
between the PMF driver and the PMFW (Power Management Firmware)
running on the SMU.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://lore.kernel.org/r/20220802151149.2123699-2-Shyam-sundar.S-k@amd.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>